Here we go, it’s going to be yet another busy week on the Plains with severe weather chances daily at least into this weekend. Let’s take a look starting with tomorrow.
It looks like we’ll be seeing some severe weather out there tomorrow, with supercells possible — most likely in Kansas.
500mb flow tomorrow in Kansas is 25-30kt which is on the marginal end for supercells and tornadoes.
60s dewpoints will also be present across Kansas tomorrow, which will be more than adequate.
Still, models are having a tendency to form storms and quickly grow them upscale, in some instances pretty early in the day. Damaging winds would still be possible if this were to occur. If supercells can occur, some very large hail will be possible.
Overall, I’m not seeing much here to point to a robust tornado threat tomorrow. The general consensus is any tornado threat will remain very low. It’s a ‘can’t rule it out day’ — especially if a storm can form and latch onto a boundary.
Things begin to change on Wednesday as an upper trough begins to emerge from the west. Moisture will surge back west, and a classic dryline should take shape, with lots of forcing arriving during peak heating. Overall, moisture profiles look pretty marginal so I’m having a hard time seeing much more than a high-based storm hail/wind threat.
Flow will begin overspreading the warm sector on Wednesday afternoon, with southerly to southwesterly flow over the dryline.
At the surface, pretty poor moisture will be present across much of the dryline, with perhaps a very narrow tongue of 60 dews stretching back towards NE Colorado.
All of this will combine to create an environment conducive for scattered to numerous thunderstorms. Storm coverage will likely end abruptly to the north in the cooler post-frontal airmass as a strong cap will be in place.
We’ll have to watch the moisture values closely on Wednesday, but most models are keeping it in the mid-40s to low 50s. Given the warm air aloft, a deeply mixed boundary layer will likely take shape. This is an environment pretty favorable for damaging winds and some large hail. The tornado threat with dryline activity on Wednesday is close to zero.
Thursday is the day I’m very interested in, but I’m not sure what to make of it. There is now a lot of agreement on the storm system coming out onto the Plains but perhaps closing off a bit. This is leading to meridional flow and poor turning of winds with height across Kansas and Nebraska but a lot of other very key details aren’t filling in just yet.
Generally speaking, a pronounced surface low will lead to a classic arcing dryline over the Plains. Rich moisture will be overspreading the warm sector with 70 dewpoints making a run as far north as Kansas.
In terms of the 500mb directional component, the GFS represents a bit of an idealized scenario with a more SW’ly direction, especially down the dryline in Oklahoma. But other models are more closed off and further south with this ejection.
One thing I’m noticing is a very early wave ejection on Thursday on some models. The Euro is breaking out a ton of precipitation that lasts throughout much of the day in the northern area of Kansas/Nebraska. To the south, forcing is much weaker and models are ranging from no storms south of I-70 to isolated supercells off of the dryline in Oklahoma on Thursday.
Right now I’ll be honest in saying I have no real confidence on how Thursday will play out. The range of options literally runs from very little severe weather to tornado outbreak. My advice: stay tuned to this blog as we’ll be keeping a close eye on this one.
As bad as predictability is on Thursday, it is kind of foolish to get into specifics beyond that. I do think Friday/Saturday could see some limited severe weather risks on the Plains before a mega ridge of high pressure builds in for a week or so. I still think some severe weather will be possible in that pattern, but I’m not sure supercells will be expected with such weak flow around.
Most likely, the return of multiple days of supercells and tornadoes will be later in May at the earliest beyond this week.